The advancement of technology development in the semiconductor field has been constrained by the existence of high-k metal gate thin film crystallization issues that lead or contribute to the degradation in dielectric properties of dielectric materials. This is the case, for example, with hafnium dioxide (HfO2), which may be used as a gate dielectric material, including for 20 nm technology and beyond.
Effective oxide thickness (EOT) scaling has been a particular challenge, due to: lack of Jg (gate leakage) improvement (i.e., the dielectric constant value is not high enough to support further scaling of high-K film thickness); and degradation in film quality in terms of the crystalline nature of the dielectric material (e.g., for HfO2, retention of desired tetragonal phase in order to achieve adequate reliability).
Attempts to address the above-described constraints include a traditionally-used post deposition anneal (PDA), but this approach causes uncontrolled interlayer (IL) regrowth without the benefit of densification and without significant improvement in the dielectric constant (k). Lanthanum (La) doping is also used in an attempt to try to address these constraints, but this approach also has its drawbacks, including the fact that its applicability is limited to nFETs due to work function (WF) constraints.
Thus, a need exists for improved semiconductor devices having a high-k dielectric, and methods of forming the same, that address high-K metal gate thin film crystallization issues and reduce degradation to the dielectric properties of dielectric materials.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicant in no way disclaims these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was, at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.